The present application claims priority to Japanese Application No. P10-182235 filed Jun. 29, 1998, which application is incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
The present invention relates to a process of forming polyimide composite electro-deposited film, suitable for use in the production of, for example, a nozzle plate of an ink jet recording head.
2. Description of the Related Art
In general, an ink jet recording head discharges ink droplets to form images of objects such as characters on a recording medium. Such an ink jet recording head has a nozzle plate, referred to also as an orifice plate, that controls positions where the ink droplets are to be discharged, as well as quantities of the ink to be discharged, in order to achieve printing with high precision.
The nozzle plate has an ink discharge nozzle constituted by a tiny hole of an inside diameter ranging from 30 to 50 xcexcm for discharging the ink and a diluting liquid nozzle that discharges a diluting liquid.
The nozzle plate is usually formed of a material which excels in heat resistance, chemical resistance, durability, excimer-laser workability and so forth, such as, for example, polyimide or polyetherimide. In order to stabilize the printing quality, an ink-repellant treatment is effected on the surface of the nozzle plate.
Ordinary ink-repellant agents such as a fluoric coating agent or fluoro-alkylsilane-type agent, however, exhibits inferior adhesion to polyimide or polyetherimide used as the material of the nozzle plate. Direct coating of such a nozzle plate material with the above-mentioned ordinary ink-repellant agent undesirably allows easy separation of the coating film and is not recommended.
Hitherto, therefore, a nozzle plate has been known having a teflon eutectoid plated layer formed directly on a flat substrate by electro-plating or electroless plating for the purpose of achieving satisfactory water- and oil-repelling characteristics, as well as anti-wear characteristics, as disclosed in Japanese Patent Laid-Open No. 4-74651.
The plating technique relying upon eutectic phenomenon, however, has a problem in that only small bonding force is produced between the water-repellant particles (teflon) in the resultant teflon eutectoid plating layer, i.e., the composite plating layer, and the metal which is nickel. In particular, the water-repellant fine particles around the nickel metal surface tend to easily come off due to, for example, wiping, allowing rapid deterioration of water- and oil-repelling performance.
When electro-plating technique is adopted, it is necessary that a underlying metallic layer such as of nickel is formed on the substrate by evaporation or sputtering. However, such a metal layer may exhibit inferior adhesion to the substrate according to the type of the substrate, leading to problems such as insufficient durability due to separation.
Electroless plating does not require formation of an underlying metallic layer, but the adhesion of the plating layer may fail to exhibit inferior adhesion, thus leading to the problem of insufficient durability due to easy separation.
Adhesion is particularly inferior when the nozzle plate is made of the aforementioned polyimide or polyetherimide which excel in the properties such as heat resistance, chemical resistance, durability and excimer-laser-perforating workability. When such materials are used, the teflon eutectoid plating film is easily separated, even if the film is formed by electroless plating.
Accordingly, it is an object of the present invention to provide a process of forming a polyimide composite electro-deposited film which excels in water-repelling performance, wear resistance or die releasing characteristic, thus offering improved durability of the ink repelling effect.
To this end, according to one aspect of the present invention, there is provided a process for forming a polyimide composite electro-deposited film, comprising the steps of: forming an electrically conductive film on at lest one side of a resin substrate; and forming, on the electrically conductive film, the polyimide composite electro-deposited film while allowing co-deposition of at least one type of eutectic fine particles selected from the group consisting of water-repellant fine particles, wear-resistant fine particles and mold-releasing fine particles.
In accordance with this process, the polyimide composite electro-deposited film is formed on the conductive film covering the resin substrate, while allowing co-deposition of one or more eutectic fine particles selected from among water-repellant fine particles, wear-resistant fine particles and mold-releasing fine particles. It is therefore possible to impart to the resin substrate one or more of the desired characteristics selected from among water-repelling performance, wear resistance or mold-releasing performance.
In accordance with another aspect of the present invention, there is provided a process for forming a polyimide composite electro-deposited film, comprising the steps of: forming, on at lest one side of a metallic substrate, the polyimide composite electro-deposited film while allowing co-deposition of at least one type of eutectic fine particles selected from the group consisting of water-repellant fine particles, wear-resistant fine particles and mold-releasing fine particles.
In accordance with this process, the polyimide composite electro-deposited film is formed on the metallic substrate, while allowing co-deposition of one or more eutectic fine particles selected from among water-repellant fine particles, wear-resistant fine particles and mold-releasing fine particles. It is therefore possible to impart to the metallic substrate one or more of the desired characteristics selected from among water-repelling performance, wear resistance or mold-releasing performance.
The above and other objects, features and advantages of the present invention will become clear from the following description when the same is read in conjunction with the accompanying drawings.